peti_silent_mode

Some macros provided by autoconf do automatically issue screen output when called, for example AC_CHECK_LIB. This may be undesirable at times, for example when these routines are called within a more complex macro consisting of several tests in a row.

Hence this macro provides a mechanism to switch screen output by autoconf generally off. All screen i/o within configure scripts takes place on file descriptor "6", which is in fact a copy of the standard output. By setting this file descriptor to "/dev/null" or to standard output again, silent mode can be enabled or disabled.

    PETI_SILENT_MODE(on)    dnl be silent
    AC_PROG_CXX
    PETI_SILENT_MODE(off)   dnl talk to me again
    AC_PROG_RANLIB

This macro was proposed and inspired by Paolo Bonzini <bonzini@gnu.org>.

AC_DEFUN([PETI_SILENT_MODE],
    [
    case "$1" in
      on)
        exec 6>/dev/null
        ;;
      off)
        exec 6>&1
        ;;
      *)
        AC_MSG_ERROR(Silent mode can only be switched "on" or "off".)
        ;;
    esac
    ])